Excitation of electrolytic condensers



Dec. 19, 1922. 1,439,526.v R. D. MERSHON.

EXCITATION 0F ELECTROLYTIC CONDENSERS.

ORIGINAL FILED JULY 18. 1917. 4 SHEETSSHEET 1.

$13 attoawug/a 1 far, W

Dec. 19, 1922.

1,439,526. R. D. MERSHON. EXCITATION 0F ELECTROLYTIC GONDENSERS.

ORIGINAL FILED JULY 18, 1917- 4 SHEETS-SHED Z.

Dec. 19, 1922. 1,439,526]

R. D. MERSHON.

EXCITATION 0F ELECTROLYTIC CONDENSERS.

ORIGINAL FILED JULY 18, 1917. 4 suns-sum 3.

E 5 5 wow wow R. D. MERSHON.

EXGITATION OF E OLYTIC CONDENSERS.

ORIGINAL JULYIB, I917. 4 SHEETS-SHEE1 4.

Dec. 19, 1922. 1,439,526.

Patented Dec. 19, 1922.

UNITED'STATES PATENT OFFICE.

RALPH D. MEBSHON, OF NEW YORK, N. Y.

EXCITATION OF ELECTROLYTIC CONDENSERS.

Application filed July 18, 1917, Serial No. 181,430. Renewed January 4, 1922. Serial No. 527,053.

To all whom it may concern:

Be it known that I, RALPH D. MnRsHoN, a citizen of the United States, residing at New York, county and State of New York, have invented certain new and useful Improvements in Excitation of Electrolytic Condensers, of which the following is a full, clear, and exact description.

It is now well understood that the functioning of an electrolytic condenser depends (among other things) upon the presence of a negative charge in the electrolyte, the value of which charge is proportional, in general, to the capacity of the condenser and to the maximum value of the E. M. F. between the condenser terminals. If for any reason this charge is diminished it will be restored by current impressed upon the apparatus This restoration is accompanied by a breaking down of the dielectric films on the electrodes. and if repeated often enough causes serious deterioration of the films with resulting decrease in the etliciency of the condenser. ()n the other hand. if the charge be maintained from some other source which does not involve flow of current from the electrolyte to the electrodes, as for example by unidirectional current delivered to the electrodes and led out by way of an unfilmed electrode or terminal immersed in the electrolyte, the aforesaid cause of impairment of the electrode-films will be eliminated. Stated otherwise. the condenser tends to operate as a rectifier, producing a unidirectional E. M. F. with a tendency for I current to flow from the electrolyte to the electrodes. If this E. M. F..be opposed by a unidirectional E. M. F. of higher value from an independent source the condenser cannot act as a rectifier and the constant charge, which the condenser must have to enable it to operate as a condenser, will be supplied and maintained by the independent source.

Heretofore it has been considered necessary to provide a separate source of unidirectional current for each condenser, a condition which, as will be readily understood, imposes a limitation upon the use of electrolytic condensers that under some circumstances may be serious. It is accordingly the chief object of my present invention to provide a system in which the same source of unidirectional current can be used with two or more condensers in series or in multiple or in series-multiple. To this and other ends the invention consists in the novel features and combinations hereinafter described.

Referring to the annexed drawings, in which several specific embodiments are shown,

Figs. 1, 2 and 3 are diagrams illustrating the operation of the electrolytic condenser, and a method of exciting the same.

Figs. 4 and 5 illustrate two embodiments in which a single source of unidirectional current is used to excite a plurality of condensers in series.

Fig. 6 illustrates an embodiment (with an odd numberof condensers in series) in which an autot-ransformer is used for connecting, in multiple with each other, all the points of infiow of unidirectional charging current to the condenser electrodes, without short-circuiting the alternating E. M. F. impressed upon the condensers when the system is in use.

Fig. '7 shows the same scheme as Fig. 6,

but with an even number of condensers.

Fig. 8 illustrates an embodiment similar to that of Fig. 4 but employing choke coils instead of an autotransformer.

Figs. 9 and 10 show other arrangements using choke coils, Fig. 10 being in other respects like Fig. 6.

Fig. 1 1 shows the arrangement of Fig. 7 changed to a series-multiple connection of the condensers.

Fig. ll shows another embodiment, advantageous for use where the series connection of the condensers is to be changed to multiple, and vice versa, and

Fig. 11 shows the corresponding multiple arrangement.

Fig. 11 shows an arrangement similar to Fig. 11.

Fig. 12 illustrates the invention embodied in a polyphase system, three-phase in the present instance. using autotransformers in the same way as in Fig. 7, the condensers being in series.

Fig. 13 also shows the invention embodied in a three-phase system, with the condensers in series, but using choke coils instead of autotransformers. 1

The operation of the electrolytic condenser as a rectifier will be readily understood from Fig. 1. In this figure, A, A, designate electrodes or plates of aluminum or other suitable metal each coated with. the necessary dielectric film (produced preferably by the method described in my prior Patent No. 1,012,889 issued December 26th, 1911), immersed in a suitable electrolyte, say a solution of borax in a vessel or tank 13. C is an electrode composed of a material. for example carbon, which is incapable of forming a dielectric film such as the plates A are coated with. For this reason C is conveniently referred to as a non-filmand will charge the battery. If the E. M. F.-

ing electrode. It is connected to a terminal D. E is an autotransformer connected to the condenser terminals F, F, and having its middle or neutral point connected to a "terminal Gr.

Imagine, now, that alternating current is impressed on the condenser terminals and that a positive impulse is coming in over the right hand terminal. The film on the right hand electrode A prevents flow of current from the latter to the electrolyte and thence to the non-filming electrode C; but since the film offers no, or but little, opposition to the flow of current from C to A, there will be a tendency for current to flow from G to D. And it will be readily seen that a like tendency exists when a negative impulse comes in over the left hand terminal F. In short, there exists between G and D a unidirectional E. M. F. If the circuit be closed from G to D the unidirectional current and E. M. F. will be pulsating; but' if no current be allowed to flow the E. of open circuit will be of nearly constant value.

Suppose, now, that we insert between G and D a source of unidirectional E. M.F. of opposite direction, as for example the source H, Fig. 2 so as to oppose the potential normally existing between G. and D. If the E. M. F. of the source H be less than the unidirectional voltage produced by the alternating E. M. F. on the condenser terminals the condenser will operate as a rectifier of the battery be just equal to the other no current will flow from or to the battery unless the negativecharge leaks away from the electrolyte; in which case current will flow from the'battery in sulficient amount to replace the charge or part of the charge so lost, thus avoiding the injury to the films, on plates A, that otherwise would occur by replacement of the charge from the alternating current impressed upon the condenser terminals F, F. However, in order to certainly insure the desired result the E. M. F. of the battery (or other D. C. source) should be in excess of that produced between G and D by the alternating E. M. F. As will be readily understood, the battery E. M. F. should be greater than the maximum voltage produced between G and D by the alternating E. M. F. impressed on the condenser.

Fig. 3 illustrates three condensers in series. A little reflection will make it clear that in a series connection of condensers such ceeeae as are shown in Figs. 1 and 2 each condenser cell contains one filming electrode, A, and

one non-filming electrode, C. Thereare thus two cells for each condenser, and the four cells of the figure therefore constitute two condensers in series. The function of the non-filming electrodes C irncells 2 and 3 is to afford electrical connection between the two electrolytes, the eii'ect being then the same as ifboth filmed electrodes A were in one cell, as in Fig. 1. In the case of cell 1, the non-filming electrode C afiords a path for the condenser or displacement current from electrode A of cell 1 to A of cell 2. From the latter, the displacement current is taken by the non-filming electrode and passed on to the electrode A in cell 4. Similarly, the displacement or condenser current from cell 4 is conducted to electrode A of cell 1. The theory and operation of the electrolytic condenser in general isexplained in my prior Patent No. 1,077,628, issued November 1, 1913, particularly lines 1 to 124 on page 3 thereof. The terminals of the autotransformer E are connected to the condenser terminals and the non-filming electrodes of the inner cells are connected through a unidirectional source H to the the alternating current comes in at the right hand terminal F the lower cells serve as electric valves, 12 and 11 offering no opposition to flow of current and 10 and 9 opposing it. When an impulse comes in at the left,'9 and 10 offer no opposition to the current while '11 and 12 oppose it. Thus a unidirectional E. M. F. is produced between I and J which is opposed by the E. M. F. of the exciting source H.

The arrangements shown in Figs. 4 and 5 possess some disadvantages aside from the fact that they require a separate cell for each filmed electrode. For example, in general the path of the displacement current through the electrolyte is longer than in an arrangement like that of Fig. 3, even though the number of condensers be made the same in each case. Also the exciting the autotransformer E; and the non-filming electrodes C, one in each cell, are connected to the autotransformer E. The terminals of the transformer E are connected to the condenser leads F, F. In these figures exciting current from the unidirectional source H is fed to the neutral point of the autotransfo rmer E and is there split up, the split currents passing in opposite directions through the autotransformer E to the filmed electrodes A, A, thence out by way of the non-filming electrodes C to the neutral point of the autotransformer E and back to the source H, in this case the exciting voltage will be only that required for a single cell, whereas in Fig. at the voltage will be twice, and in Fig. 5 four times, that required for one cell.

It is to be noted that in Figs. 6 and 7 the autotransformers have to carry only the resultant of the exciting current of the transformer and the exciting current of the condensers. That is, the rating of the autotransformers will be much less than the K.V.A. of the condensers.

The use of autotransformers, though in general preferable, is not. necessary, as choke coils can be used instead. Thus in Fig. 8 is shown an arrangement like Fig. 4 but employing choke coils M, M, instead of the autotransformer E. Choke coils, are also used in Figs. 9 and 10. Since the unidirectional exciting current is inevitably somewhat pulsating when alternating current is impressed on the system, the choke coils will cut down to some extent the unidirectional voltage impreswd upon the condensers. This is one reason why autotransformers are preferable. In most if not all cases where choke coils are employed they should be of the open magnetic circuit type so that their cores will not be saturated.

The invention readily lends itself to the series-multiple operation of the condensers. Thus the series arrangement shown in Fig. 7 can be changed to series-multiple by putting the two cells at the ends of the series into series withj each other but in parallel with the middle cells. as shown in Fig. 11. In this case, that is, where a series connection is changed to series-multiple, parts of the autotransformers are idle in the latter connection, as indicated in F ig. 11. Of

course if only a series-multiple arrangement is desired the transformers would be constructed accordingly, without unused coils.

Of course other methods can be employedfor obtaining a multiple arrangement of condensers from a series arrangement. For example the series system illustrated in Fig. 11 can be changed to multiple without altering the transformer connections in any Way. In this figure the exciting current from the source H is split up by the autotransformers E and E. The several cur-' rents thus produced are deliveredto the filmed electrodes A, reuniting at the nonfilming electrodes C and in the autotrans former E. IVhen it is desired to change to the multiple connection it is only nec essary to make the necessary changes in the interconnections of the condensers, leaving the transformer connections exactly as they are. The result is illustrated in Fig. 11, in which it will be seen that the filmed electrodes A are in multiple and connected to the terminal F of the system-and that the.

electrodes A are in multiple and connected to the terminal F the transformer connections remaining as in Fig. 11.

The embodiment illustrated in Fig. 11 is similar to that shown in Fig. 11, but has an even number of condensers. Also, the transformer E of Fig. 11 .is divided into two in Fig. 11, and. an additional transformer, E is provided, with its terminals connected to the neutral points of the two transformers E Each of the electrodes A thus receives exciting current through all the transformers, thereby equalizing the current; whereas in Fig. 11 the exciting current for the center condenser does not flow through the turns of transformer E but goes directly to the center transformer E; Similarly, in Fig. 11 the transformer E is divided into two, and the neutral points of the two are connected to the terminals of an additional transformer E which latter is connected by its neutral point to the unidirectional source H.

From the foregoing the connections for polyphase work will be readily understood by those skilled in the art. and itis therefore deemed unnecessary to illustrate the same, but I give two examples of threehase systems. The arrangement shown in ig. l2 employs autotransformers, E, E, in the same manner as in Fig. 7, for example. In Fig. 13 choke coils M are used instead of autotransformers, in the same manner as in Fig. 10.

It will be observed that the autotrans formers and the choke coils not only constitute means for connecting the filmed and non-filmed electrodes (or some of them) in multiple to the source of unidirectional exciting-current, so that the exciting current is split up into separate currents and the latter supplied to the filmed electrodes,

electrodes to the unidirectional source, arenever short-circuited. It will be evident that the nature, of the unidirectional source used, whether it be, for example, a battery, 2. generator, or a rectifier fed by the main or a separate A. C. circuit, is in general immaterial, and that in any practical application of the invention the choice of one or another will depend upon the particular conditions and circumstances involved.

It is to be understood that the invention is not limited to the specific arrangements herein illustrated and described, but can be embodied in other forms without departure from its spirit.

I claim:

1. The combination with a system of electrolytic condensers, two or more of which are in series, of a single source of unidirectional current for exciting the condensers, and means for splitting up the exciting current to' the system and simultaneously opposing counter-electromotive forces to alternating voltages existing between the paths of the split current when alternating current is impressed upon the system.

2. The combination with a system'of electrolytic condensers, two or more of which are in series, of a single source of unidirectional current for exciting the condensers,

and transforming means connecting one pole of the unidirectional source with the filmed electrodes of the system and transforming means connecting the other pole of said source with the several electrolytes, to split up the exciting current into a plurality of current-s and oppose counter-electromotive forces to alternating voltages existing between the paths of the unidirectional exciting currents when alternating current is impressed upon the system.

3. The combination with a system of electrolytic condensers, two or more of which are in series, of a single source of unidirectional current for exciting the condensers, and an autotransformer connecting one pole of the unidirectional source with the filmed electrodes of the condensers and an autotransformer connecting the other pole of said source with the several electrolytes, to split up the exciting current into a plurality of currents and oppose counter-electromotive forces to alternating voltages existing between the paths of the unidirectional exciting currents when alternating current is impressed upon the system.

4. The combination with a plurality of inter-connected electrolytic condensers, of'a single source of unidirectional current for exciting the condensers, and means donnected with the condensers and the unidirectional source to split up the current from the latter into a plurality of unidirectional currents and acting in both the series and the multiple connection of the condensers to oppose counter electromotive forces to alternating voltages between the paths of said plurality of unidirectional currents.

5. The combination of a plurality of electrolytic condensers, means for connecting the condensers in series to a source of alternating current, a single source of unidirectional current, and means connecting the condenser electrodes in multiple to the unidirectional source for exciting the condenser, the last-mentioned means including devices adapted to prevent short-circuiting of alternating voltages between the condenser electrodes.

6. The combinationof a plurality of electrolytic condensers, a multiple connection for the electrolytes acting to produce counter electro-motive forces to. alternating voltages among the electrolytes and providing a neutral point among the latter; a multiple connection for the condenser-electrodes acting to produce counter electro-motive forces to alternating voltages among the condenser-electrodes and providing a neutral point among the latter; and means for feeding unidirectional current into the latter neutral point and out of the first, to excite the condensers.

In testimony whereof I affix my signature.

RALPH D. MERSHON. 

